Ships_Cat
Well-Known Member
But if you trimmed two identical Sillouettes, except one being heavier than the other, that same way the lighter boat would be faster.
John
John
Wetted area or length?
- Thread starter jimi
- Start date
Twister_Ken
Well-Known Member
Might be confusing transom drag (=turbulence = bad) with wetted surface drag.
AlienP2
Well-Known Member
On a sillouette you could generally keep the transom out of the water by both sitting forward in the cockpit (and taking the outboard off before the start of the race /forums/images/graemlins/blush.gif). I would regard that as good practice though on all points of the wind. Ditto overall weight reduction if the boat is sitting too low in the water.
The racing I used to do was pretty low key, most people were living on their boats for the week and there was a gentlemans agreement that you didn't strip the boat down to bear essentials after breakfast. As I've said in other posts, I do this for fun.
The racing I used to do was pretty low key, most people were living on their boats for the week and there was a gentlemans agreement that you didn't strip the boat down to bear essentials after breakfast. As I've said in other posts, I do this for fun.
jimi
Well-Known Member
[ QUOTE ]
that you didn't strip the boat down to bear essentials after breakfast.
[/ QUOTE ]
What .. no honey then .. Oh Pooh!
that you didn't strip the boat down to bear essentials after breakfast.
[/ QUOTE ]
What .. no honey then .. Oh Pooh!
Sailfree
Well-Known Member
[ QUOTE ]
The more of a boat that's in the water, the more hydrodynamic drag there is to keep it slowed down. So there's benefit in getting much of it out of the water and up into the air.
[/ QUOTE ]
To play devils advocate why do longer displacement boats go faster than short boats
The more of a boat that's in the water, the more hydrodynamic drag there is to keep it slowed down. So there's benefit in getting much of it out of the water and up into the air.
[/ QUOTE ]
To play devils advocate why do longer displacement boats go faster than short boats
Robin
Well-Known Member
[ QUOTE ]
To play devils advocate why do longer displacement boats go faster than short boats
[/ QUOTE ]
Because the maximum is set by the wave formation at around 1.4 x Sqrt of LWL and to achieve the maximum requires significantly more power for the last 10% than the other 9 x 10%s - or look at it another way, going at 60% max requires little power and 60% of 9kts (the longer boat) is faster than 60% of 6kts (the smaller boat), each hull should have (sail or motor) no trouble achieving 60% of hull speed in light winds or flat seas, so the longer is always faster. QED!
To play devils advocate why do longer displacement boats go faster than short boats
[/ QUOTE ]
Because the maximum is set by the wave formation at around 1.4 x Sqrt of LWL and to achieve the maximum requires significantly more power for the last 10% than the other 9 x 10%s - or look at it another way, going at 60% max requires little power and 60% of 9kts (the longer boat) is faster than 60% of 6kts (the smaller boat), each hull should have (sail or motor) no trouble achieving 60% of hull speed in light winds or flat seas, so the longer is always faster. QED!
Blueboatman
Well-Known Member
At low speeds wetted area = friction,thus a long keel will be slower than a fin and skeggy.As speeds increase it is all about hull form,skinny long canoe form is good,especially when aided by extra stern overhang ..But you knew that.
Suggest remove girt big paddle wheel propellor to improve performance,or ''charge batteries'' with engine and allow prop shaft to turn simultaneously..
Suggest remove girt big paddle wheel propellor to improve performance,or ''charge batteries'' with engine and allow prop shaft to turn simultaneously..
